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Landscape Message: May 19, 2023

Landscape Message: May 19, 2023
May 19, 2023

UMass Extension's Landscape Message is an educational newsletter intended to inform and guide Massachusetts Green Industry professionals in the management of our collective landscape. Detailed reports from scouts and Extension specialists on growing conditions, pest activity, and cultural practices for the management of woody ornamentals, trees, and turf are regular features. The following issue has been updated to provide timely management information and the latest regional news and environmental data.

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Scouting Information by Region

Environmental Data

The following data was collected on or about May 17, 2023. Total accumulated growing degree days (GDD) represent the heating units above a 50ºF baseline temperature collected via regional NEWA stations ( for the 2023 calendar year. This information is intended for use as a guide for monitoring the developmental stages of pests in your location and planning management strategies accordingly.

MA Region/Location


Soil Temp
(°F at 4" depth)

(Gain since last report)

Time/Date of Readings

(Gain since last report)

2023 Total



CAPE 72 204 60 56 0.02 12:00 PM 5/17/2023
SOUTHEAST 78 221 76 53 0 3:00 PM 5/17/2023
NORTH SHORE 82 183 60 52 0 10:00 AM 5/17/2023
EAST 96 242 67 56 0 4:00 PM 5/17/2023
METRO 77 200 59 53 0.004 5:30 AM 5/17/2023
CENTRAL 85 220 57 54 0 11:30 AM 5/17/2023
PIONEER VALLEY 74 209 60 56 0 11:00 AM 5/17/2023
BERKSHIRES 52 161 59 53 0 6:30 AM 5/17/2023


Indicator Plants - Stages of Flowering (BEGIN, BEGIN/FULL, FULL, FULL/END, END)
Robinia pseudoacacia (black locust) * Begin * * * * * *
Syringa meyeri (Meyer lilac) Begin * * * * * * Begin
Deutzia spp. (deutzia species) * End * * * * * Begin
Aesculus hippocastanum (common horsechestnut) Begin/Full Full Full Begin Begin Begin Full Begin/Full
Enkianthus campanulatus (redvein enkianthus) Begin * Full Begin Begin Begin Full *
Rhododendron carolinianum (Carolina rhododendron) Begin/Full * Full Begin Begin Begin/Full Begin/Full Begin
Rhododendron catawbiense (catawba rhododendron) * Begin * Begin Begin Begin Begin *
Spiraea x vanhouttei (Vanhoutte spirea) Full Full Full Full/End Full/End Full/End Full/End Full
Elaeagnus umbellata (autumn olive) Full Full/end Full/End Full/End Full/End Full/End Full/End Begin
Syringa vulgaris (common lilac) Full Full/end Full Full Full Full Full Full
Cornus florida (flowering dogwood) Full End Full Full Full Full Full Full
Rhododendron spp.(early azaleas) Full Full/End Full/End Full Full Full/End Full/End Full/End

Regional Notes

Cape Cod Region (Barnstable)

General Conditions:The average temperature from May 10th through May 17th was 61ºF with a low of 41ºF on May 15th and a high of 82ºF on May 12th.   Highs have generally been in the 70s and lows generally in the 50s.  The weather seems unseasonably warm for the Cape for the time of year, but a delight with sunny and mostly sunny days.  During the period there was no significant precipitation.  Soil moisture is short and the area is abnormally dry.  Windy days have resulted in high evaporative losses from soil and plants.  Watering recently transplanted plant material requires extra attention. 

Some herbaceous plants seen in bloom include fringed bleeding heart (Dicentra eximia), basket of gold (Aurinia saxitilis), Solomon’s seal (Polygonatum odoratum), columbine (Aquilegia spp.), bearded iris (Iris x germanica), and lupine (Lupinus spp.).  Woody plants seen in bloom include doublefile viburnum (Viburnum plicatum var. tomentosum), chokeberry (Aronia melanocarpa), dwarf fothergilla (Fothergilla gardenii), weigela (Weigela florida) redbud (Cercis canadensis), crabapples (Malus domestica) and beach plum (Prunus maritima).  Oaks in the red oak group are ending flowering, oaks in the white oak group almost in full bloom.  

Pests/Problems: Winter injury is still an important topic.  Hydrangea macrophylla and butterfly bush should be thoroughly pruned to remove dead stems before the shoots from base get much larger.  Flowering of some woody ornamentals has been less than usual including flowering cherry, forsythia, and some azaleas. Whether this is a response to cold injury or the previous season’s drought is not clear – possibly both.

Winter moth and fall canker worm are present in low numbers and causing holes in the leaves of many species. Other insects or insect damage observed include Eastern tent caterpillar on black cherry (Prunus serotina), viburnum leaf beetle on arrowwood viburnum (Viburnum dentatum), adult sawflies were observed ovipositing on rose (soon to hatch into rose slug sawfly larvae), red lily leaf beetle on Asiatic lilies, elder shoot borer damage on elderberry (Sambucus nigra) and white grubs in turf.  Slug damage was observed on bearded iris (Iris x germanica).

Beech leaf disease symptoms (R. Norton) Beech leaf disease severe symptoms: Damaged buds and leaves. (R. Norton) Beech leaf disease which was identified on the Cape for the first time last year and has since been found to be fairly widespread, occurring in most large stands of beech on the Cape.  Some infected trees have been severely impacted by the disease and have reduced and damaged foliage so far this year.  Other disease symptoms or signs observed during the period include tulip fire on tulip, leaf spot on ink berry (Ilex glabra), leaf spot on mountain laurel (Kalmia latifolia), shothole disease on cherry laurel (Prunus laurocerasus), sycamore anthracnose on sycamore (Platanus occidentalis).  Senescence (yellowing and abscission) of older leaves (which is often misidentified as disease) is occuring American holly (Ilex opaca). 

Weeds seen in bloom during the period include autumn olive (Eleagnus umbellata), bush honeysuckles (Lonicera spp.), garlic mustard (Alliaria petiolata), common cinquefoil (Potentilla simplex), thymeleaf speedwell (Veronica serpyllifolia), common violet (Viola papilionacea), yellow rocket (Barbarea vulgaris), black medic (Medicago lupulina) and cypress spurge (Euphorbia cyparissias).

Ticks are active – keep yourself protected!  Rabbits are feeding on emerging perennials.

Southeast Region (Dighton)

General Conditions: Mid-May weather has been lovely albeit more than a tad dry. We've had no measurable precipitation over the past week. The National Weather Service has issued a red flag warning due to very dry conditions and declared a critical fire hazard. The daytime high temperature for the week was 79ºF on Thursday, May 19th. The overnight low skirted frost at 33ºF on Wednesday the 17th. The average temperature for the week was 55ºF. The windiest day was Tuesday the 16th, with winds averaging 22 mph. 

Plants in flower: Aesculus hippocastanum (horse-chestnut), Aquilegia (columbine), Arisaema triphyllum (jack-in-the-pulpit), Aurinia saxatilis (basket-of-gold), Calycanthus floridus (Carolina allspice), Cerastium tomentosum (snow-in-summer), Conium maculatum (poison hemlock), Cornus kousa (Chinese dogwood), C. sericea (red-osier dogwood), Crataegus (hawthorn), Cytisus scoparius (Scotch broom), Dianthus (pinks), Elaeagnus umbellata (Autumn olive), Euonymus alatus (burning bush), Euphorbia (spurge), Fothergilla (witch-alder), Geranium maculatum (wild geranium), G. sanguine (blood geranium), Hesperis matronalis (dame's rocket), Heuchera (coral bells), Hyacinthoides hispanica (Spanish bluebell), Iberis umbellata (garden candytuft), Iris germanica (bearded iris), I. pseudacorus (yellow flag), I. siberica (Siberian iris), Lamprocapnos spectabilis (bleeding heart), Leucothoe fontanesiana (highland doghobble), Liriodendron tulipifera (tulip tree), Lupinus (bluebonnets), Ilex x meserveae (Meserve hybrid holly), Nepta (catnip), Ornithogalum (star-of-Bethlehem), Phlox stolonifera (creeping phlox), Polygonatum biflorum  (Solomon's seal), Prunus serotina (black cherry), Rhododendron catawbiense (Catawba hybrid rhododendrons), R. mollis (Exbury azaleas), (deciduous & hybrid azaleas), Robinia pseudoacacia (black locust), Rosa rugosa (beach rose), Spiraea prunifolia (bridal-wreath spirea), S. × vanhouttei (Vanhouttei spirea), Syringa vulgaris (common lilac), S. × persica (Persian lilac), Vaccinium corymbosum (northern highbush blueberry), Viburnum plicatum (Japanese snowball, double-file viburnum), Vinca minor (myrtle)

Schools of mummichogs are very active along the shoreline with the incoming tides. 

Pests/Problems: Red flag warnings in effect for fire hazards due to winds and dry conditions. 

Cutworm caterpillars in rough turf. European pine sawfly larvae on mugo pine and Austrian pine are an inch long. Two spot spider mites on white spruce produce copious webbing. Hard ticks are questing. Second instar deer ticks may carry Lyme disease. Wear light-colored clothing so that they are easier to spot. Tuck in trousers legs and inspect yourself carefully after being in areas, such as tall grass or shrubbery along the ecotone, that may harbor ticks. Use insect repellents. Oak pollen is heavy and ubiquitous, covering surfaces with a green-yellow sheen and causing sneezing and coughing in allergy sufferers. Rainfall has been disappointing once again.

North Shore (Beverly)

General Conditions: Dry weather with clear sunny skies and strong winds persisted most days during this period. There was no precipitation recorded at Long Hill during the last seven days. Temperatures continued to be above normal for this time of the year. Daytime temperatures ranged from low 60s to low 80s with nighttime temperatures ranging from low 40s to mid 50s. The average daily temperature was 61ºF, with a high of 82ºF recorded May 12th. A low of 41ºF was recorded on May 17th. Many plants were observed in bloom. Woody plants seen in bloom include: silver bell (Halesia carolina), Wright viburnum (Viburnum wrightii), beach plum (Prunus maritima), large Fothergilla (Fothergilla major), dwarf Fothergilla (Fothergilla gardenii), flowering dogwood (Cornus florida), little leaf lilac (Syringa microphylla), pink shell azalea (Rhododendron vaseyi), single seed hawthorn (Crataegus monogyna), pearlbush (Exochorda racemosa), redbud (Cercis canadensis), common horse chestnut (Aesculus hippocastanum, Kwanzan cherry (Prunus serrulata), black Chokeberry (Aronia melanocarpa), tree peony (Paeonia suffruticosa), and highbush blueberry (Vaccinium corymbosum). Blooming herbaceous plants include: scotch rose (Rosa spinosissima), Father Hugo rose (Rosa hugonis), honesty plant (Lunaria annua), yellow archangel (Lamiastrum galeobdolon), blue-eyed Mary (Omphalodes verna), Solomon's seal (Polygonatum biflorum), bleeding heart (Dicentra spectabilis), water forget-me-not (Myosotis palustris), red barrenwort (Epimedium x rubrum), rue anemone (Anemonella thalictroides), and fetterbush (Leucothoe fontanesiana).

Viburnum leaf beetle on arrowwood viburnum (G. Njue) Rose slug sawfly (G. Njue) Woolly beech aphid (G. Njue) Pests/Problems:  Because of dry weather and strong winds the national weather service issued fire danger alerts most of the days during this period. Due to the dry conditions, some of the perennial and annual plants on exposed dry sandy soils are starting to show signs of water stress. We need rain! Fortunately the weekend forecast calls for rain on Saturday. Young larvae of viburnum leaf beetle (Pyrrhalta viburni) were observed starting to feed on leaves of susceptible Viburnum cultivars. Young roseslug or rose sawfly (Endelomyia aethiops) caterpillars were observed starting to cause damage on some climbing roses. Roseslugs skeletonize leaves, leaving the veins intact. Rose aphids (Macrosiphum rosae) were observed feeding on rose buds. Rose aphids feed on tender shoots and buds. High populations can reduce the quality and quantity of flowers. Black cherry aphids (Myzus cerasi) were also observed on kwanzan cherry (Prunus serrulata). These aphids cause curling on  foliage and reduce terminal growth.  Woolly beech aphids (Prociphilus fagi) were observed on beeches. Woolly aphids aphids produce a covering of fluffy white wax. Beech leaf disease (BLD) was also observed on beeches. Dandelion (Taraxacum officinale), Lesser celandine (Ranunculus ficaria), Ground Ivy (Glechoma hederacea), Violets (Viola spp.) and Purple Deadnettle (Lamium purpureum) are in full bloomBecause of the warm weather ticks are very active and mosquitoes are also active. Be careful to protect yourself when working outdoors.

East (Boston)

General Conditions: The past week was warm and dry. Daytime temperatures averaged 77ºF with a high of 85ºF on the 12th. Overnight temperatures averaged 50ºF with a low of 40ºF on the 10th. We received zero precipitation over the past seven days. Plants in bloom include: Aesculus x carnea (red horse-chestnut), Iberis umbellata (garden candytuft), Phlox divaricata (woodland phlox), Prunus serotina (black cherry) and Rosa rugosa (beach rose).

Pests/Problems: Soil conditions are dry. Recent transplants require supplemental irrigation. We have received 0.88 inches of total precipitation in May. We last recorded 0.04 inches on May 8th. Some woody shrubs; Clethra alnifolia (summersweet), Itea virginica (Virginia sweetspire) and Rhus aromatica (fragrant sumac) continue to struggle to fully leaf out. Garlic mustard (Arrilaria petiolata) is forming seed. Field bindweed (Convolvulus arvensis) and black swallow-wort (Cynanchum louiseae) have emerged.

Metro West (Acton)

General Conditions: Dry, windy, and warm sums up this last week’s weather. A trace of precipitation was recorded on two days, strong winds continued, and summer-like temperatures were recorded most days. We went from spring to early summer in one week.  A high temperature of 84ºF was recorded on the 12th and was preceded and followed by a high of 81ºF on the 11th, 13th, and 16th. According to NOAA, the 20-year average monthly rainfall for May is 3.37” and as of the 16th I have recorded a mere 1.03”.

Pests/Problems: High temperatures recorded this past week were into the 70s and 80s and that combined with little to no precipitation, 0.004” to be exact, creates a lot of stress for plants. Water restrictions are already in effect in some nearby communities as are campfires. This dry and windy weather is also a concern for wildfires and without the help of rain from mother nature, fires are a real threat and can burn for days.

Central Region (Boylston)

General Conditions: Temperatures during this reporting period had the large swings we’re accustomed to at this time of year, from high-30’s to mid-80’s with no precipitation. Many migratory birds have been spotted, including ruby-throated hummingbird and Baltimore oriole. Early spring blooms are petering out. Tulips are just about finished. Noted in bloom this period: Dwarf fothergilla (Fothergilla gardenia), Korean spice viburnum (Viburnum carlesii), red horse chestnut (Aesculus pavia), and nodding trillium (Trillium cernuum). Many oak species are in full bloom, leading to copious amounts of pollen covering cars and causing seasonal allergy sufferers much distress.

Pests/Problems: The dry weather is a concern given the time of year. May 1st was the last significant rainfall, with just trace amounts throughout the rest of the month. Soils are drying out. Red flag warnings were issued throughout the region and the risk of forest fires is quite high. No significant pests were observed during the reporting period, but it’s apparent now that many woody plants were impacted by the deep freeze we experienced in early February. Throughout the region, most weeping cherries (Prunus × subhirtella ‘Pendula’) have not leafed out nor flowered and are likely dead. Also of note, Japanese scholar tree (Styphnolobium japonicum) is showing substantial deadwood throughout the canopy.

Pioneer Valley (Amherst)

General Conditions: After an extended period of cool and wet weather from late April into early May, it’s been warm, dry and windy since May 6th.. The trifecta of full sun, low humidity (RH <25%) and persistent afternoon winds are drying out surface soils. There’s still good moisture at lower horizons but recently transplanted trees, shrubs, perennials and annuals have required regular irrigation. By late afternoon on many days this past reporting period, temperatures have been close to 80ºF and wind gusts of 15–25 mph have been whipping new plant growth. Some limited rainfall is predicted in the long-term forecast (5/20–21), but the area needs a good soaking soon. The landscape is full of rich, new growth with varying shades of green on display. Spruce, hemlock, juniper and true fir are all pushing bright green needles and shoots. Dogwood, horse chestnut, viburnums, snowbells, and weigela, among other flowering trees and shrubs are in bloom. Oak seedlings are very abundant right now in landscape beds, seemingly growing several inches overnight. Red maple (Acer rubrum) samaras are falling in huge volumes throughout the valley and this appears to be a mast year for many trees. Norway maples (A. platanoides) appear to have a heavy seed set as well but are not yet falling. Oak pollen is waning although in general, tree pollen is still plentiful in the air, especially with the constant winds. We are still a few weeks away from eastern white pine pollen, which can be the worst period in the pollen season for those with allergies. In a very troubling development, the NWS enacted a freeze warning across the tri-counties for the early morning hours of 5/18, with lows predicted in the high 20s in some locations. If this forecast holds, it will take a few days to sort out which plants were injured. Frost/freeze injury symptoms can manifest in several ways, depending on the plant. For deciduous trees and shrubs, it may appear as premature shedding of the newest foliage along with tan to dark-colored blotches on older foliage. Foliage may be distorted in shape as it develops as some portions are injured while others remain healthy. In some cases, the leaf margins are blighted while in others, the freeze occurs within interveinal portions at the base of the leaf. On conifers, tender new shoots and needles may be killed outright and these will become brown over the course of several days.  

Larvae of the European pine sawfly (Neodiprion sertifer) on mugo pine (Pinus mugo). Photo by N. Brazee Pests/Problems: Beech leaf disease sightings in Hampshire County remain limited, in both forest and landscape settings. But new occurrences and intensifying disease symptoms are being reported. Sycamore anthracnose (Apiognomonia veneta) often plagues American sycamore (Platanus occidentalis) this time of year. Currently, sycamores in Hampshire County are thin and ragged with leaves in varying stages of development. However, it’s far too early to determine if this is a “good” or “bad” year, as trees can remain very sparse into June and still recover. Several mature London planetree (P. × acerifolia) on the UMass campus are also struggling to leaf out due to anthracnose this spring. Typically, London planetree is very resistant to sycamore anthracnose but the abundant rain in late April likely allowed for disease development. Larvae of the European pine sawfly (Neodiprion sertifer) were detected on a group of mugo pines (Pinus mugo) (see photo) on the UMass campus. Dozens of larvae were handpicked and the trees were then treated with spinosad. Large clusters of sawfly larvae will feed on older needles right now as new shoots and needles elongate. While this pest is very common on mugo pine, it will also attack a variety of other two- and three-needle pines. Occasionally, it can be found on five-needle pines, like P. strobus. Unlike the redhead pine sawfly (N. lecontei), larvae of the European pine sawfly blend in very well against the dark green color of the needles, making them more challenging to locate without careful scouting. Japanese knotweed (Polygonum cuspidatum) is already >10’ tall in some locations and increasingly can be found in upland sites away from its typical riparian habitat.

Berkshire Region (West Stockbridge)

General Conditions: The highest temperatures over the latest scouting period occurred late last week, with the peak being on May 12th: 82ºF in North Adams, 80ºF in Pittsfield, and 79ºF in Richmond. Since then, a chill has settled in.  Scattered frost was reported at many locations on the morning of May 12th.  Low temperatures recorded at the three NEWA sites were: 32ºF on May 12th in North Adams, 36ºF on May 12th in Richmond, and 38ºF on May 17th in Pittsfield. It is expected that all sites in the County will experience a frost on the morning of Thursday, May 18th. In many areas, the temperature could be in the range of a hard freeze. Aside from a hard freeze, the biggest concern, weatherwise, in this area is the lack of rainfall. The last rainfall which amounted to at least 0.1 inch was on May 4th. Soil moisture is generally quite low though not at the point of causing any obvious effects on established landscape plants. The general landscape is quite colorful with a wide range of early season bloomers on full display. New plantings will certainly require some irrigation.

Pests/Problems:  Despite optimism that this year would see a decline in the population of spongy moths (Lymantria dispar), they are now being seen in rather large numbers feeding on the recently emerged foliage of many tree and shrub species.  Besides oaks, large numbers were found feeding on birch, beech, apple, and cherry species, as well as on roses at sites in Stockbridge and West Stockbridge. Other pests observed this week were boxwood psyllids, adult lily leaf beetles, Eastern tent caterpillars, elongate hemlock scale, and aphids (on roses). Also found were the eggs of imported willow leaf beetles.

Regional Scouting Credits

  • CAPE COD REGION - Russell Norton, Horticulture and Agriculture Educator with Cape Cod Cooperative Extension, reporting from Barnstable.
  • SOUTHEAST REGION - Brian McMahon, Arborist, reporting from the Dighton area.
  • NORTH SHORE REGION - Geoffrey Njue, Green Industry Specialist, UMass Extension, reporting from the Long Hill Reservation, Beverly.
  • EAST REGION - Kit Ganshaw & Sue Pfeiffer, Horticulturists reporting from the Boston area.
  • METRO WEST REGION – Julie Coop, Forester, Massachusetts Department of Conservation & Recreation, reporting from Acton.
  • CENTRAL REGION - Mark Richardson, Director of Horticulture reporting from New England Botanic Garden at Tower Hill, Boylston.
  • PIONEER VALLEY REGION - Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, reporting from Amherst.
  • BERKSHIRE REGION - Ron Kujawski, Horticultural Consultant, reporting from Great Barrington.

Woody Ornamentals


Recent pests and pathogens of interest seen in the UMass Extension Plant Diagnostic Lab, a select few:

Beach leaf disease (BLD) symptoms should be apparent as trees continue to leaf out. The Massachusetts DCR Forest Health group has unveiled a new online reporting form for new BLD detections, found here:

Brown rot, caused by Monilinia, on Ussurian pear (Pyrus ussuriensis ′MorDak′). The tree is approximately 30-years-old and resides in a landscaped bed on the corner of a parking lot. It receives afternoon sun in well-drained, loam-based soils. Air spading around the tree was recently conducted to improve growing conditions. This spring, new growth was blighted and there was branch flagging scattered throughout the canopy. Last  year, the tree was nearly defoliated by the end of the growing season. Brown rot is uncommon (even rare) on pear but it is a documented host for the pathogen. Typically, Monilinia occurs primarily on stone fruits (Prunus). The pathogen was abundant on fruits, petioles and symptomatic foliage. It frequently causes shoot tip dieback on infected trees early in the growing season. Also present was Gymnosporangium (rust) and Phomopsis. The latter was found on dead shoot tips and likely contributed to last year’s defoliation. Drought stress and heat from 2022 has likely weakened this tree.

Dieback of a recently transplanted blue spruce (Picea pungens) due to transplant shock, winter injury, Rhizosphaera needle cast (Rhizosphaera kalkhoffii) and stem cankering by Setomelanomma holmii. The tree (8′ tall) was transplanted to the site in September of 2022 and watered regularly after installation. The site includes full sun in well-drained soils but persistent winds are a feature. In late winter (February), needles throughout a large section of the tree became reddish-brown and were prematurely shedding. Rhizosphaera is a well-known pathogen of blue spruce but a great deal remains unknown about Setomelanomma. The fungus has been associated with a condition called sudden needle drop (SNEED) and can be regularly found on blue spruce throughout the region. However, its pathogenicity has not been confirmed in controlled trials. Wind burn and desiccation likely played a large role in the needle loss.

Coral spot nectria canker (Nectria cinnabarina) on wisteria (Wisteria macrostachya 'Blue Moon'). The plant is approximately 10-years-old and has been present at the site for six years. It receives full sun in sandy soils at the base of a slope. Recently, the soil was amended with compost to improve moisture retention. This spring, sections did not leaf out and coral-colored spore masses were observed on the stems. These represent spore-bearing pads that have ruptured through the outer bark. When numerous they are highly distinctive. The host plant (wisteria) helps to illustrate the wide array of plants that Nectria can attack. It’s possible that drought stress predisposed the plant to infection.

Phytophthora root rot of Hicks yew (Taxus × media ′Hicksii′). Several trees in a hedge row that are around 15-years-old and receive full sun. The soils are clay-based with moderate drainage and irrigation is provided. Last summer, yellowing needles and stunted growth was observed. Yews are remarkably drought-resistant once established and typically only require supplemental water during extended dry periods on well-drained soils. The irrigation likely saturated the heavy soil at times, providing ideal conditions for Phytophthora. This common and widespread pathogen requires wet soils to sporulate and cause disease in most cases and this is a good example of how overwatering can be detrimental to plant health.

Botryosphaeria stem and branch cankering (Botryosphaeria sp.) on a saucer magnolia (Magnolia × soulangeana). The tree is roughly 30-years-old and experiences a mixture of sun and shade in an established, residential landscape. Soil drainage is poor and despite sandy loam soils the area can be wet. Major canopy dieback has developed in recent years with half of the tree dying. Botryosphaeria was very abundant on the submitted stems and will readily attack weakened and stressed trees.

Report by Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, UMass Amherst.

Insects and Other Arthropods

Resource for Birds, Butterflies, Bees, and Beneficials in Managed Landscapes:

Ohio State University Extension just recently released a resource that discusses the value of many native trees and shrubs as resources providing food and habitat for wildlife including but not limited to songbirds, hummingbirds, wild and specialist bees, and caterpillar (immature) and adult butterflies and moths. Highlighted species include:

  • Birch (Betula spp.)
  • Black gum (Nyssa sylvatica)
  • Cherry and plum (Prunus spp.)
  • Crabapple (Malus spp.)
  • Eastern redbud (Cercis canadensis)
  • and more!

To learn more, visit:

Interesting Insects Reported or Seen Recently:

  • Aphids found within curled leaves on Viburnum spp. plants in Hampshire County, MA on 5/13/2023. (Photo: Tawny Simisky, UMass Extension.) Leaf distortion and curling on Viburnum spp. plants fed upon by aphids seen in Hampshire County, MA on 5/13/2023. (Photo: Tawny Simisky, UMass Extension.) One of three Viburnum spp. plants in full sun with extensive leaf curling and distortion from aphid feeding. (Photo: Tawny Simisky, UMass Extension.) Aphids on Viburnum: There are a few different species of aphids that might be present and causing leaf-twisting-and-curling symptoms on certain species of viburnum. Perhaps one of the most discussed of those being the snowball aphid (Ceruraphis viburnicola) which is often found on Viburnum opulus, V. prunifolium, and V. acerifolia. However, in the case of these aphids seen on 5/13/2023 in Hampshire County, MA, it seems a different species of aphid may be involved. In the case of the damage seen in these photos, the aphids found within the twisted and curled leaves were gray to light-brown/orange in color. This is in contrast to snowball aphid immatures, which may be white to light green in color (with round stem mothers appearing as if they have been rolled in white powdered sugar). The coloration and pattern of leaf folding seen here looks more like Aphis viburni, or the viburnum aphid. This species is reported from Europe and southern England, however it has also been reported in older literature from Illinois, also on Viburnum opulus (Thomas, 1877*). For more detailed images of Aphis viburni, visit: . Another possibility is Aphis fabae, or the black bean aphid, which oddly enough is also known to viburnum. However, the leaf curling pattern completed by that species may be a little different than what was observed here. For more detailed images of Aphis fabae, visit: . At this point, most of the damage and leaf distortion has already been completed. In the case of these observations, three plants in full sun were severely distorted. *Title: A List of the Species of the Tribe Aphidini, family Aphidae, found in the United States, which have been heretofore named, with descriptions of some New Species. Cyrus Thomas, 1877.
  • Feeding damage and leaf rolling by the oak leafrolling weevil seen on 5/12/2023 in Middlesex County, MA. (Photo: Tawny Simisky, UMass Extension.) Leaf rolling by the oak leafrolling weevil seen on 5/12/2023 in Middlesex County, MA. (Photo: Tawny Simisky, UMass Extension.) Oak Leafrolling Weevil: Synolabus bipustulatus (synonym Attelabus bipustulatus) is a small, stout, shiny, black weevil with two red spots, one on each elytra (hardened hindwing). (Another oak leaf rolling weevil species exists, Homoeolabus analis, but that insect is primarily orange in color with the exception of a black head and legs.) Weevils of this species (S. bipustulatus) are less than ¼ inch in size. The exact timing of this insect’s life cycle in Massachusetts is not completely understood. Adult weevils chew slits on either side of the midrib of the host plant leaf, where they will lay an egg at the tip of the leaf. The leaf is then folded (by the weevil) along the midrib and rolled into a tidy cylinder, kind of like a sleeping bag. By the end of this rolling, the egg is positioned near the center of the roll. Evidence of such leaf rolling was seen on oak in Middlesex County, MA on 5/12/2023. These weevils have been previously reported as active in Middlesex County in June of 2021. Once the egg hatches, the immature weevil larva (which is legless, curved, and plump with a brown head) feeds on the tissue inside the rolled leaf. Once the larva matures, it pupates inside the rolled leaf. Adults emerge again to continue the life cycle and there may be multiple generations per year in certain locations of this insect’s geographic range. Leafrolling weevils have been noted on 16 species of oak and 2 species of chestnut. These insects are rarely considered pests, as they typically do not cause noticeable damage to their host plants. Management is seldom considered necessary.

Insects and other Arthropods

  • Deer Tick/Blacklegged Tick: Ixodes scapularis adults are active all winter and spring, as they typically are from October through May, and “quest” or search for hosts at any point when daytime temperatures are above freezing. Engorged females survive the winter and will lay 1,500+ eggs in the forest leaf litter beginning around Memorial Day (late May). For images of all deer tick life stages, along with an outline of the diseases they carry, visit: .

Anyone working in the yard and garden should be aware that there is the potential to encounter deer ticks. The deer tick or blacklegged tick can transmit Lyme disease, human babesiosis, human anaplasmosis, and other diseases. Preventative activities, such as daily tick checks, wearing appropriate clothing, and permethrin treatments for clothing (according to label instructions) can aid in reducing the risk that a tick will become attached to your body. If a tick cannot attach and feed, it will not transmit disease. For more information about personal protective measures, visit: . 

The Center for Agriculture, Food, and the Environment provides a list of potential tick identification and testing resources here:

In the news: UMass Amherst has now been designated as the location for the New England Center of Excellence in Vector-Borne Diseases (NEWVEC). This CDC (Centers for Disease Control and Prevention) funded center will work to reduce the risk of vector-borne diseases spread by ticks, mosquitoes, and other blood-sucking insects or insect relatives in New England: . For more information and to contact NEWVEC, visit: . To contact the center for more information about their Spring 2023 Project ITCH (“Is Tick Control Helping”), visit: .

Note: Dog ticks (Dermacentor variabilis) continue to be noticeably active in parts of Berkshire and Hampshire County in 2023. They are present in large numbers this year even in environments where tick activity is typically low, such as in mowed lawns.

  • Mosquitoes: According to the Massachusetts Bureau of Infectious Disease and Laboratory Science and the Department of Public Health, there are at least 51 different species of mosquito found in Massachusetts. Mosquitoes belong to the Order Diptera (true flies) and the Family Culicidae (mosquitoes). As such, they undergo complete metamorphosis, and possess four major life stages: egg, larva, pupa, and adult. Adult mosquitoes are the only stage that flies and many female mosquitoes only live for 2 weeks (although the life cycle and timing will depend upon the species). Only female mosquitoes bite to take a blood meal, and this is so they can make eggs. Mosquitoes need water to lay their eggs in, so they are often found in wet or damp locations and around plants. Different species prefer different habitats. It is possible to be bitten by a mosquito at any time of the day, and again timing depends upon the species. Many are particularly active from just before dusk, through the night, and until dawn. Mosquito bites are not only itchy and annoying, but they can be associated with greater health risks. Certain mosquitoes vector pathogens that cause diseases such as West Nile virus (WNV) and eastern equine encephalitis (EEE).  For more information about mosquitoes in Massachusetts, visit: . There are ways to protect yourself against mosquitoes, including wearing long-sleeved shirts and long pants, keeping mosquitoes outside by using tight-fitting window and door screens, and using insect repellents as directed. Products containing the active ingredients DEET, permethrin, IR3535, picaridin, and oil of lemon eucalyptus provide protection against mosquitoes. Be aware that not all of these can be safely used on young children. Read and follow all label instructions for safety and proper use. For more information about mosquito repellents, visit: and
  • Wasps/Hornets: Many wasps are predators of other arthropods, including pest insects such as certain caterpillars that feed on trees and shrubs. Adult wasps hunt prey and bring it back to their nest where young are being reared, as food for the immature wasps. A common such example are the paper wasps (Polistes spp.) who rear their young on chewed up insects. They may be seen searching plants for caterpillars and other soft-bodied larvae to feed their young. Paper wasps can sting, and will defend their nests, which are open-celled paper nests that are not covered with a papery “envelope”. These open-celled nests may be seen hanging from eaves or other outdoor building structures. Aerial yellow jackets and hornets create large aerial nests that are covered with a papery shell or “envelope”. Common yellow jacket species include those in the genus Vespula. Dolichovespula maculata is commonly known as the baldfaced hornet, although it is not a true hornet. The European hornet (Vespa crabro) is three times the size of a yellow jacket and may be confused for the northern* giant hornet (Vespa mandarinia). The European hornet is known to Massachusetts, but the northern giant hornet is not. If you are concerned that you have found or photographed a northern giant hornet, please report it here: . Paper wasps and aerial yellowjackets overwinter as fertilized females (queens) and a single female produces a new nest annually in the late spring. Queens start new nests, lay eggs, and rear new wasps to assist in colony/nest development. Nests are abandoned at the end of the season. Some people are allergic to stinging insects, so care should be taken around wasp/hornet nests. Unlike the European honeybee (Apis mellifera), wasps and hornets do not have barbed stingers, and therefore can sting repeatedly when defending their nests. It is best to avoid them, and if that cannot be done and assistance is needed to remove them, consult a professional.

Highlighted Invasive Insects & Other Organisms Update:

  • Newly hatched spongy moth caterpillars have ballooned and settled on host plants to begin feeding on newly opened leaves in Millers Falls, MA as seen on 5/2/2023. Photo courtesy of: Nicole Keleher, MA Department of Conservation and Recreation, Forest Health Program. Spongy moth egg mass (T. Simisky) Spongy moth egg masses were seen hatching in Erving, MA on 5/2/2023. Photo courtesy of: Nicole Keleher, MA Department of Conservation and Recreation, Forest Health Program. Spongy moth egg masses were seen hatching in Great Barrington, MA on 4/18/2023. Photo courtesy of: Tom Ingersoll. Spongy Moth: Lymantria dispar

    Spongy moth egg hatch was reported on April 18, 2023, in Great Barrington, MA (Berkshire County). The tiny caterpillars can be seen on top of the egg mass from which they hatched in the photo courtesy of Tom Ingersoll. Spongy moth egg hatch has also been reported from Erving, MA and Millers Falls, MA (Franklin County) on 5/2/2023. Tiny caterpillars were observed to be dispersing and settling on host plant leaves and beginning to feed. See photos courtesy of Nicole Keleher, MA Department of Conservation and Recreation, Forest Health Program.

Spongy moth caterpillars may again be noticeable in parts of Berkshire County and abutting locations in NY and CT this year, as well as parts of Franklin County that were impacted in 2022. This is despite seeing caterpillar die-off from the spongy moth killing fungus Entomophaga maimaiga last season.

For more information from the MA Department of Conservation and Recreation, Forest Health Program, visit: and look under the spongy moth navigation tab.

If large numbers of egg masses are seen, plan to monitor them between 90-100 growing degree days (roughly the first week in May, but this varies) to better time egg hatch and caterpillar emergence. The MA Department of Conservation and Recreation, Forest Health Program reports that winter counts of spongy moth egg masses are higher than hoped for in parts of Berkshire County coming into the spring of 2023. This may mean that spongy moth caterpillars will again be noticeable in these areas this year, despite seeing caterpillar die-off from the spongy moth killing fungus Entomophaga maimaiga last season. For more information from the Forest Health Program, visit: and look under the spongy moth navigation tab.

If egg masses are plentiful near high-value specimen trees in Berkshire County in 2023, consider applying the reduced risk insecticide Bacillus thuringiensis Kurstaki (Btk) to host plant leaves before caterpillars are over ¾ inch in length. Work with a licensed pesticide applicator and arborist to plan these applications, if necessary, especially if a high-value host plant was defoliated by this insect in 2021 or 2022.

Additionally, we’ve been asked about wrapping trees to prevent spongy moth caterpillars from accessing the canopy to feed. Here is some information. If you are interested in wrapping trees or shrubs with a sticky barrier to capture older, crawling spongy moth caterpillars, there are a few things to consider. 1) This will not prevent all caterpillars from accessing the tree to feed, nor is it a guarantee that no foliage will be eaten by them on the plant to which it has been applied. 2) This will not prevent the tiniest of caterpillars (newly hatched) from ballooning on the wind into tall trees and settling to feed. For example, this could mean that caterpillars will still have some access to the leaves following their dispersal in the spring. 3) Do not apply any sticky substances directly to the tree or shrub bark to avoid risk of injury to the plant. 4) Sticky bands will need to be monitored frequently throughout the growing season, particularly in mid-to-late May and especially June, to clean and replace them.

If the bands become covered in dead caterpillars, living ones can crawl over the dead and still access the leaves of the tree. It is recommended that bands be placed on trees (and sticky material on the bands) once the caterpillars are approximately an inch in length. This may be approximately in early or mid-June. Bands should then be left up and changed frequently through July, until the caterpillars have pupated. This technique may work best with an engaged property owner that is willing and able to frequently check and help change the bands. For more information, visit:

The good news – homeowners in central and eastern Massachusetts will hopefully not have to worry too much about spongy moth this year. It may be undetectable in many central and eastern MA locations. MA DCR reports not seeing significant overwintering spongy moth egg masses in those locations. The primary area of concern includes parts of southwestern Berkshire County and areas in Franklin County that were impacted in 2022.

For more information about spongy moth, view the first episode of InsectXaminer, here: .

Why did the common name for Lymantria dispar change recently? More information is available here: .

  • Hemlock Woolly Adelgid (T. Simisky) Hemlock Woolly Adelgid: Adelges tsugae is present on eastern and Carolina hemlock. The overwintering hemlock woolly adelgid generation (sistens) is present through mid-spring and produces the spring generation (progrediens) which will be present from early spring through mid-summer. HWA, unlike many other insects, does most of its feeding over the winter. Hemlock woolly adelgid winter mortality (due to two significant regional cold snap events) is expected to be high for 2023. HWA that were most likely to survive these extreme cold events are those on lower host tree branches, if they were insulated by snow pack at the time. Determine if HWA are alive or dead on host plants before making chemical management decisions. This can be done quickly in the field by squishing overwintered HWA in their ovisacs between your thumb and forefinger and looking for a dark brown/blackish stain (from the hemolymph, or insect blood). If staining does not occur, the insect may have died and dried up. Test at least a few insects on at least a few branches to determine if any are alive. (Much more extensive examination may involve viewing at least 200 adelgids per site/location to calculate percent winter mortality.)

Eggs may be found in woolly masses at the base of hemlock needles beginning in mid-March. Each woolly mass is created by a female who may then lay 50-300 eggs. Eggs hatch and crawlers may be found from mid-March through mid-July. Infested trees may be treated with foliar sprays in late April to early May, using Japanese quince as a phenological indicator. Systemic* applications may be made in the spring and fall, or when soil conditions are favorable for translocation to foliage. Nitrogen fertilizer applications may make hemlock woolly adelgid infestations worse.

For more information, visit: .

*Note: beginning July 1, 2022 systemic insecticides known as neonicotinoids (including imidacloprid) have become state restricted use for tree and shrub uses in Massachusetts. More information is available, here:

  • Spotted Lantern Fly egg masses (T. Simisky) Spotted Lanternfly: (Lycorma delicatula, SLF) is a non-native, invasive insect that feeds on over 103 species of plants, including many trees and shrubs that are important in our landscapes. It overwinters as an egg mass, which the adult female insect lays on just about any flat surface. Pictures of egg masses can be seen here:

    States south of Massachusetts (Virginia to Pennsylvania) have begun reporting spotted lanternfly egg hatch for 2023. The MA Department of Agricultural Resources expects that spotted lanternfly eggs should begin hatching in Massachusetts over the course of May. For further updates from MDAR, visit: .

    Currently, the only established populations of spotted lanternfly in Massachusetts are in Fitchburg, Shrewsbury, Worcester, and Springfield MA. Therefore, there is no reason to be preemptively treating for this insect in other areas of Massachusetts. If you suspect you have found spotted lanternfly in additional locations, please report it immediately to MDAR here: . If you are living and working in the Fitchburg, Shrewsbury, Worcester, and Springfield, MA areas, please be vigilant and continue to report anything suspicious.

For More Information:

From UMass Extension:

*New*: Spotted Lanternfly Management Guide for Professionals:

*Note that management may only be necessary in areas where this insect has become established in Massachusetts, and if high value host plants are at risk. Preemptive management of the spotted lanternfly is not recommended.

Fact Sheet:

Check out the InsectXaminer Episode about spotted lanternfly adults and egg masses! Available here:

From the MA Department of Agricultural Resources:

Fact Sheet and Map of Locations in MA:

Spotted Lanternfly Management Guide for Homeowners in Infested Areas:

  • Asian Longhorned Beetle: (Anoplophora glabripennis, ALB) Look for signs of an ALB infestation which include perfectly round exit holes (about the size of a dime), shallow oval or round scars in the bark where a female has chewed an egg site, or sawdust-like frass (excrement) on the ground nearby host trees or caught in between branches. Be advised that other, native insects may create perfectly round exit holes or sawdust-like frass, which can be confused with signs of ALB activity. 

The regulated area for Asian longhorned beetle is 110 square miles encompassing Worcester, Shrewsbury, Boylston, West Boylston, and parts of Holden and Auburn.  If you believe you have seen damage caused by this insect, such as exit holes or egg sites, on susceptible host trees like maple, please call the Asian Longhorned Beetle Eradication Program office in Worcester, MA at 508-852-8090 or toll free at 1-866-702-9938.

To report an Asian longhorned beetle find online or compare it to common insect look-alikes, visit: or .

This wood-boring beetle readily attacks ash (Fraxinus spp.) including white, green, and black ash and has also been found developing in white fringe tree (Chionanthus virginicus) and has been reported in cultivated olive (Olea europaea). Signs of an EAB infested tree may include D-shaped exit holes in the bark (from adult emergence), “blonding” or lighter coloration of the ash bark from woodpecker feeding (chipping away of the bark as they search for larvae beneath), and serpentine galleries visible through splits in the bark, from larval feeding beneath. It is interesting to note that woodpeckers are capable of eating 30-95% of the emerald ash borer larvae found in a single tree (Murphy et al. 2018). Unfortunately, despite high predation rates, EAB populations continue to grow. However, there is hope that biological control efforts will eventually catch up with the emerald ash borer population and preserve some of our native ash tree species for the future.

  • Winter Moth: (Operophtera brumata) data since 2017 has indicated that the winter moth population in eastern Massachusetts has been on the decline while the percent of winter moth pupae parasitized by Cyzenis albicans has increased! Dr. Joseph Elkinton’s laboratory at UMass Amherst has released this biological control agent of winter moth since 2005 and conducted the rigorous sampling required to determine where the insect has established and what its impact on the winter moth population has been at multiple sites in eastern MA.

The take-home point? Do not worry about winter moth this spring! In fact, management of this insect in landscaped settings will likely not be necessary in most locations. Blueberry growers may still, on the other hand, be interested in scouting and continuing to monitor for this insect, as only very low numbers of winter moth caterpillars might be tolerated in that system.

For blueberry and apple growers in Rhode Island, check out this winter moth update from Heather Faubert (University of Rhode Island) for April 13, 2023: .

In recent years, it is worth-while to note that some areas on the Cape and other locations in eastern MA have reported noticeable native cankerworm populations in the spring, which are often confused for winter moth. Read more about cankerworms in the spring scouting list below.

  • Jumping Worms: Amynthas spp. earthworms, collectively referred to as “jumping or crazy or snake” worms, overwinter as eggs in tiny, mustard-seed sized cocoons found in the soil or other substrate (ex. compost). Immature jumping worms hatch from their eggs by approximately mid-to-late May. It may be impossible to see them at first, and it may be more likely that jumping worms are noticed when the first adults begin to appear at the end of May and in June. It is easy to misidentify jumping worms (ex. mistake European earthworms for jumping worms) if only juveniles are found. In August and September, most jumping worms have matured into the adult life stage and identification of infestations is more likely to occur at that time of year.

For More Information:

UMass Extension Fact Sheets:

Spring Scouting Suggestions & Preparation for Upcoming Tree & Shrub Insects (Native and Invasive):

  • Andromeda Lace Bug: Stephanitis takeyai is most commonly encountered on Japanese Andromeda. Eggs are tiny and inserted into the midveins on the lower surface of the leaf and covered with a coating that hardens into a protective covering. 5 nymphal stages are reported. Nymphs are different in appearance from the adults, often covered with spiky protrusions. 3-4 generations per year have been observed in New England, with most activity seen between late-May into September (starting at approximately 120 GDD’s, Base 50°F). Both nymphs and adults can be seen feeding on leaf undersides. Adults have delicate, lace-like wings and what appears to be an "inflated hood" that covers their head. Adults are approximately 1/8 of an inch long. Arrived in the US in Connecticut in 1945 from Japan (Johnson and Lyon, 1991).

    Can cause severe injury to Japanese andromeda, especially those in full sun. Mountain Andromeda (Pieris floribunda) is highly resistant to this pest. Like other lace bugs, this insect uses piercing-sucking mouthparts to drain plant fluids from the undersides of the leaves. Damage may be first noticed on the upper leaf surface, causing stippling and chlorosis (yellow or off-white coloration). Lace bug damage is distinguished from that of other insects upon inspecting the lower leaf surface for black, shiny spots, "shed" skins from the insects, and adult and nymphal lace bugs themselves.

    A first sign of potential lace bug infestation is stippling or yellow/white colored spots or chlorosis on host plant leaf surfaces. Lace bugs excrete a shiny, black, tar-like excrement that can often be found on the undersides of infested host plant leaves. Flip leaves over to inspect for this when lace bug damage is suspected.

    Mountain Andromeda (Pieris floribunda) is considered to be highly resistant to this insect and can be used as an alternative for such plantings, along with other lace bug-resistant cultivars. Consider replacing Japanese Andromeda with mountain andromeda as a way to manage for this pest. Natural enemies are usually predators, and sometimes not present in large enough numbers in landscapes to reduce lace bug populations. Structurally and (plant) species complex landscapes have been shown to reduce azalea lace bug (Stephanitis pyrioides) populations through the increase of natural enemies.

  • Arborvitae Leafminer: In New England and eastern Canada, four species of leafminers are known to infest arborvitae. These include Argyresthia thuiella, A. freyella, A. aureoargentella, and Coleotechnites thujaella. The arborvitae leafminer, A. thuiella, is the most abundant of these and has the greatest known range when compared to the others. (It is also found in the Mid-Atlantic States and as far west as Missouri). Moths of this species appear from mid-June to mid-July and lay their eggs. The damage caused by all of these species is nearly identical. Trees, however, have been reported to lose up to 80% of their foliage due to arborvitae leafminer and still survive. At least 27 species of parasites have been reported as natural enemies of arborvitae leafminers, the most significant of which may be a parasitic wasp (Pentacnemus bucculatricis). Arborvitae leafminer damage causes the tips of shoots and foliage to turn yellow and brown. If infestations are light, prune out infested tips.
  • Azalea Lace Bug: Stephanitis pyrioides is native to Japan. The azalea lace bug deposits tiny eggs on the midveins on leaf undersides. They then cover the area where the egg was inserted with a brownish material that hardens into a protective covering. Each female may lay up to 300 eggs (University of Florida). Nymphs hatch from the eggs and pass through 5 instars. The length of time this takes depends on temperature. Between 2 and 4 generations may be completed in a single year. In Maryland, there are four generations per year. Adults are approximately 1/10 of an inch in length with lacy, cream colored, transparent wings held flat against the back of the insect. Wings also have black/brown patches. Adults of this species also possess a "hood" over their head. Nymphs are colorless upon hatch from the egg, but develop a black color as they mature and are covered in spiny protrusions. 

    Immatures and adults use piercing-sucking mouthparts to remove plant fluids from leaf tissues. This feeding leaves behind white-yellow stippling on the upper surface of host plant leaves, even though the insects themselves feed on the underside of the leaf. Plants in full sun are often particularly damaged by these insects. In heavy infestations, plants in full sun may be killed by the feeding of the azalea lace bug. 

    Begin scouting for azalea lace bugs when 120 GDD’s (Base 50°F) are reached. This species is active throughout the summer, following. Look for dark, black tar-like spots of excrement deposited by immature and adult lace bugs on the underside of susceptible host plant leaves, especially on leaves with white-yellow stippling visible on the upper surface. If lace bugs are not already known to the location, check susceptible hosts located in full sun first. Monitor plants for lace bug feeding from late April through the summer.

    Plant azaleas in partial shade. Resistance has been reported in Rhododendron atlanticum, R. arborescens, R. canescens, R. periclymenoides, and R. prunifolium.

    Many of the natural enemies reported for this insect are predators. They are rarely abundant enough to reduce damaging populations of lace bugs, especially on plants in sunny locations. Structurally and (plant) species complex landscapes have been shown to reduce azalea lace bug (Stephanitis pyrioides) populations through the increase of natural enemies.

  • Azalea Sawflies: There are a few species of sawflies that impact azaleas. Johnson and Lyon's Insects that Feed on Trees and Shrubs mentions three of them. Amauronematus azaleae was first reported in New Hampshire in 1895 and is likely found in most of New England. Adults of this species are black with some white markings and wasp-like. Generally green larvae feed mostly on mollis hybrid azaleas. Remember, sawfly caterpillars have at least enough abdominal prolegs to spell “sawfly” (so 6 or more prolegs). Adults are present in May, and females lay their eggs and then larvae hatch and feed through the end of June. There is one generation per year. Nematus lipovskyi has been reared from swamp azalea (Rhododendron viscosum). Adults of that species have been collected in April (in states to the south) and May (in New England) and larval feeding is predominantly in late April and May in Virginia and June in New England. One generation of this species occurs per year, and most mollis hybrid azaleas can be impacted. A third species, Arge clavicornis, is found as an adult in July and lays its eggs in leaf edges in rows. Larvae are present in August and September. Remember, Bacillus thuringiensis Kurstaki does not manage sawflies.
  • Bagworm (T. Simisky) Bagworm:Thyridopteryx ephemeraeformis is a native species of moth whose larvae construct bag-like coverings over themselves with host plant leaves and twigs. This insect overwinters in the egg stage, within the bags of deceased females from last season. Eggs may hatch and young larvae are observed feeding around mid-June, or roughly between 600-900 GDD’s. Now is the time to scout for and remove and destroy overwintered bags. In recent years, an increase in bagworm activity (particularly in urban forests) in Massachusetts has been noticed by professionals. Thus far in 2023, reports have been made from Plymouth County, MA. More information can be found here:
  • Boxwood Leafminer: Monarthropalpus flavus partly grown fly larvae overwinter in the leaves of susceptible boxwood. Yellowish mines may be noticeable on the undersides of leaves. This insect grows rapidly in the spring, transforming into an orange-colored pupa. After pupation, adults will emerge and white colored pupal cases may hang down from the underside of leaves where adults have emerged. Adults may be observed swarming hosts between 300-650 GDD’s, or roughly the end of May through June. Most cultivars of Buxus sempervirens and B. microphylla are thought to be susceptible. If installing new boxwoods this spring, resistant cultivars such as ‘Vardar Valley’ and ‘Handsworthiensis’ are good choices at sites where this insect has been a problem. For more information, visit:
  • Boxwood Mite: Eurytetranychus buxi overwinter as tiny eggs on boxwood leaves and hatch mid-spring. These mites are tiny (about the size of a period) and difficult to detect. Feeding may cause plants to appear off-color. If management is deemed necessary, the timing for treatment may be between 245-600 GDD’s.
  • Boxwood Psyllid: Psylla buxi feeding can cause cupping of susceptible boxwood leaves. Leaf symptoms/damage may remain on plants for up to two years. English boxwood may be less severely impacted by this pest. Eggs overwinter, buried in budscales, and hatch around budbreak of boxwood. Eggs may hatch around 80 GDD’s. While foliar applications may be made between 290-440 GDD’s, the damage caused by this insect is mostly aesthetic. Therefore, typically, management is not necessary. For more information, visit: .
  • Cankerworms: Alsophila pometaria (fall cankerworm) and Paleacrita vernata (spring cankerworm) are often confused for winter moth (Operophtera brumata). Cankerworm populations in eastern MA, particularly on areas of Cape Cod, were confused for winter moth in 2019. Spring cankerworm adults are active in February and March, and fall cankerworm adults are active in late November into early December. During these times, both species lay eggs. These native insects most commonly utilize elm, apple, oak, linden, and beech. Eggs of both species hatch as soon as buds begin to open in the spring. Caterpillars occur in mixed populations and are often noticeable by mid-May in MA. Young larvae will feed on buds and unfolding leaves. There are two color forms (light green and dark) for caterpillars of both species. Like winter moth, they will drop to the soil to pupate. This usually occurs in June. Fall cankerworm larvae have three pairs of prolegs (one of which is small so it is sometimes referred to as ½) and spring cankerworm have two pairs. (Winter moth caterpillars also have 2 pairs of prolegs.) If populations are large and damage is noticeable on hosts, reduced risk insecticides such as Bacillus thuringiensis Kurstaki or spinosad may target larvae between approximately 148-290 GDD’s.

    For more information, visit: and

  • Dogwood Borer: Synanthedon scitula is a species of clearwing moth whose larvae bore not only into dogwood (Cornus), but hosts also include flowering cherry, chestnut, apple, mountain ash, hickory, pecan, willow, birch, bayberry, oak, hazel, myrtle, and others. Kousa dogwood appear to be resistant to this species. Signs include the sloughing of loose bark, brown frass, particularly near bark cracks and wounds, dead branches, and adventitious growth. The timing of adult emergence can be expected when dogwood flower petals are dropping and weigela begins to bloom. Adult moth flights continue from then until September. Emergence in some hosts (ex. apple) appears to be delayed, but this differs depending upon the location in this insect’s range. Eggs are laid singly, or in small groups, on smooth and rough bark. Female moths preferentially lay eggs near wounded bark. After hatch, larvae wander until they find a suitable entrance point into the bark. This includes wounds, scars, or branch crotches. This insect may also be found in twig galls caused by other insects or fungi. Larvae feed on phloem and cambium. Fully grown larvae are white with a light brown head and approx. ½ inch long. Pheromone traps and lures are useful for determining the timing of adult moth emergence and subsequent management.

  • Dogwood SawflyMacremphytus tarsatus has one generation per year. The larvae of the dogwood sawfly overwinter in decaying wood and occasionally compromised structural timber. An overwintering "cell" is created in this soft wood. Pupation occurs in the springtime and adults can take a lengthy time to emerge, roughly between late May and July. 100+ eggs are laid in groups on the underside of leaves. Eggs hatch and the larvae feed gregariously, initially skeletonizing leaves. As the caterpillars grow in size, they are capable of eating the entire leaf with the exception of the midvein. Larval appearance varies greatly throughout instars, so much so that one might mistake them for multiple species. Early instars are translucent and yellow, but as the caterpillars grow they develop black spots (over yellow) and become covered in a white powder-like material. Larvae and their shed skins may resemble bird droppings. Full grown larvae begin to wander in search of a suitable overwintering location. Rotting wood lying on the ground is preferred for this.

    Foliage of dogwood, especially gray dogwood (Cornus racemosa) may be impacted. Skeletonizes leaves at first, then eats all but the midvein.

  • Eastern Spruce Gall Adelgid: Adelges abietis is a pest of Norway spruce primarily, but occasionally damages other spruce species such as Colorado blue, white, and red spruce. This adelgid overwinters as a partially grown female, often referred to as a stem mother. This overwintering individual matures around bud break and lays 100-200 eggs. The eastern spruce gall adelgid may be targeted for management between 22-170 GDD’s, base 50°F (mid-April to early-May).

The eastern spruce gall adelgid may be targeted for management between 22-170 GDD’s, base 50°F (mid-April to early-May).

Egg hatch typically occurs when wild cherry leaves begin to unfold and young caterpillars may emerge by late-April through the first two weeks in May (90-190 GDD’s).

This insect is non-native, and was introduced into the United States from Europe before 1900. Galls are small, sometimes pineapple shaped/variable, but produced on the basal portion of the shoots, such that the twig extends beyond the gall. Twig dieback may occur.

  • Eastern Tent Caterpillar: Malacosoma americanum eggs overwinter on host plant twigs. Egg hatch typically occurs when wild cherry leaves begin to unfold and young caterpillars may emerge by late-April through the first two weeks in May (90-190 GDD’s). Susceptible hosts include cherry and crabapple. Other host plants whose leaves are fed upon by this native insect can include apple, ash, birch, willow, maple, oak, poplar, and witch-hazel. Where practical, prune out and remove new eastern tent caterpillar tents before they become larger as the caterpillars continue to feed. Eastern tent caterpillars are native to Massachusetts and have many associated natural enemies (parasites and predators) that help regulate populations. Unless these caterpillars are actively defoliating specimen trees in a landscaped setting, we can coexist with this particular herbivore native to our forests.
  • Elongate Hemlock Scale: Fiorinia externa is found on eastern, Carolina, and Japanese hemlock, as well as yew, spruce, and fir. The elongate hemlock scale may overwinter in various life stages, and overlap of many developmental stages at any given time can be observed throughout much of the season.

Treatments for the crawler, or mobile, stage of this insect may be made in late May through mid-June, or between 360-700 GDD’s, base 50°F.

Treatments for the crawler, or mobile, stage of this insect may be made in late May through mid-June, or between 360-700 GDD’s, base 50°F. Nitrogen fertilizer applications may make elongate hemlock scale infestations worse.

For more information, visit: .

  • Elm Leaf Beetle: Xanthogaleruca (formerly Pyrrhaltaluteola is found on American elm (Ulmus americana; not preferred), Chinese Elm (Ulmus parvifolia; not preferred), English Elm (Ulmus procera; preferred host), Japanese Zelkova (Zelkova serrata), and Siberian Elm (Ulmus pumila; preferred host).

This species was accidentally introduced into the eastern United States early in the 1800's. Since then, it has been found throughout the USA anywhere elms are located. It also occurs in eastern Canada. The adult elm leaf beetle overwinters in protected areas, such as the loose bark of trees, but can also be a nuisance when it tries to invade homes in search of overwintering protection. Beetles will try to enter houses or sheds in the fall. 

In the spring, the adult beetles will fly back to the host plant and chew small, semi-circular holes in the leaves. The adult female can lay 600-800 yellow eggs in her life. Eggs are laid in clusters on the leaves and resemble pointy footballs. Larvae are tiny, black, and grub-like when they hatch from the egg. Young larvae will skeletonize the undersides of leaves. As they grow in size, the larvae become yellow-green with rows of black projections. Oldest larvae may appear to have two black stripes along their sides, made from the black projections. There are 3 larval instars. Mature larvae will wander down the trunk of the host tree and pupate in the open on the ground at the tree base or in cracks and crevices in the trunk or larger limbs. They spend approximately 10 or so days as a pupa, and then the adults emerge. Those adults will fly to the foliage of the same host plant or other adjacent potential hosts in the area, where they will lay eggs. In the fall, the adults will leave the host plant in search of overwintering shelter. In most locations in the USA, two generations of this insect are possible per year. In warmer locations, 3-4 generations per year are possible.

Leaves are skeletonized by the larvae. Skeletonization may cause the leaf to turn brown or whitish. Adults are capable of chewing through the leaf, often in a shothole pattern. When in very large populations, they are capable of completely defoliating plants. Populations of this insect can fluctuate from year to year, and often management is not necessary if populations are low. However, defoliation for consecutive seasons may lead to branch dieback or death of the entire tree.

  • Euonymus Caterpillar: Yponomeuta cagnagella is of European origin and widespread in distribution throughout Europe. It was first reported in North America in Ontario in 1967. The euonymus caterpillars (larvae) feed in groups and envelop the foliage of the host plant in webs as they feed. Hosts include: Euonymus europaeus (tree form), E. kiautschovicus, E. alatus, and E. japonicus. Mature caterpillars are just under an inch in length, creamy yellow-gray in color with black spots and a black head capsule. By late June, these larvae pupate in white, oval-shaped cocoons which are typically oriented together vertically either on host plants or non-hosts in the area. Cocoons can be found in cracks and crevices, or webbed together leaves. The adult moth emerges in late June in most locations. The adult female secretes a gummy substance over her eggs which will harden, making them even more difficult to see. Eggs hatch by mid-August, at which time the tiny larvae prepare to overwinter beneath their eggshell-like covering. These larvae are inactive until the following year, when caterpillars group together to feed on newly emerging leaves, creating a mess of webs as they feed. There is one generation per year. Plants may be partially or entirely defoliated. Management of young, actively feeding caterpillars with Bacillus thuringiensis is possible if deemed necessary, however many species of Euonymus are considered invasive themselves.

    Check out Episode 3 of InsectXaminer to see the euonymus caterpillar in action and learn more about its life cycle:

  • Euonymus Scale: Unaspis euonymi is an armored scale that can be found on euonymus, holly, bittersweet, and pachysandra. This insect can cause yellow spotting on leaves, dieback, and distorted bark. For crawlers, early June timing is suggested between 533-820 GDD’s for management. (Eggs begin to hatch in early June.)
  • European Pine Sawfly: Neodiprion sertifer overwinters in the egg stage. Eggs are laid by females the previous season by cutting slits in needles using their ovipositors and depositing 6-8 eggs in each of 10-12 needles. Egg hatch occurs from late-April to mid-May and caterpillars become active roughly between 78-220 GDD, base 50°F. The primary host in MA is Mugo pine but it can be found on Scots, red, jack, and Japanese red pine. It is also found on white, Austrian, ponderosa, shortleaf, and pitch pine when planted near the aforementioned species.  This dark colored caterpillar feeds in tight groups and small numbers can be pruned or plucked out of host plants and destroyed. Spinosad products can be used whenever the caterpillars are actively feeding, usually by mid-May and when caterpillars are still small. Bacillus thuringiensis kurstaki is not effective against sawflies.
  • Fletcher Scale: Parthenolecanium fletcheri is a soft scale pest of yew, juniper, and arborvitae. Feeding scales, especially on yew, result in honeydew and sooty mold, needle yellowing, and at times, premature needle drop. There is one generation per year. Overwintered second instar nymphs can be targeted between 38-148 GDD's, base 50°F. Nymphs develop and adult females lay eggs (on average 500-600) in May that hatch by June.  Dead females conceal egg masses beneath. Crawlers migrate short distances to branches and may be concentrated on certain branches of a particular plant.
  • Forest Tent Caterpillars (T. Simisky) Forest Tent Caterpillar: Malacosoma disstria egg hatch occurs between 192-363 GDD’s, base 50°F, by mid-late May and caterpillars may be active for at least 5-6 weeks following. Susceptible hosts whose leaves are fed on by this insect include oak, birch, ash, maple, elm, poplar, and basswood. This native insect has many natural enemies, including some very effective pathogens that typically regulate populations. However, outbreaks of this insect can occur on occasion.
  • Hemlock Looper: Two species of geometrid moths in the genus Lambdina are native insects capable of defoliating eastern hemlock, balsam fir, and white spruce. Adult moths lay their eggs on the trunk and limbs of hosts in September and October, and eggs will hatch by late May or early June. (L. fiscellaria caterpillars may be active between 448-707 GDD’s.) Monitor susceptible hosts for small, inch-worm like caterpillars. Where populations are low, no management is necessary. Hemlock loopers have several effective natural enemies.
  • Holly Leafminers: Seven species of leaf miners feed on holly. Phytomyza ilicicola is usually referred to as the native holly leafminer. This species is known to feed on Ilex opaca, I. crenata, and related cultivars; however, it only lays its eggs in American holly (Ilex opaca). Some research suggests that the native holly leafminer may lay its eggs in other Ilex species, but that the larvae are unable to complete their development. This insect is found throughout the native range of its host plants. Larvae overwinter in leaf mines and pupation occurs in March and April and adult emergence by mid-May (192-298 GDD’s, base 50°F). Adult flies are known to emerge over a period of 6 or so weeks in the spring. Females lay eggs using their ovipositor on the underside of newly formed leaves. A tiny green blister forms on the leaf as the first symptom of injury. Larvae hatch from the egg and create a narrow mine that may appear brown from the upper leaf surface. Mines are broadened in the fall and a large blotch is completed in the winter. Larvae are yellow maggots and reach 1.5 mm. in length when mature. Current year’s mines are easily overlooked due to the slow feeding patterns of the larvae. Premature leaf drop may occur. Remove and destroy mined leaves before May. Phytomyza ilicis is usually only referred to as the holly leafminer, and it is a non-native species introduced from Europe and only feeds on Ilex aquifolium. (The native holly leaf miner does not develop in I. aquifolium.) The biology and damage this insect causes is similar to that of the native holly leafminer, with the exception of the fact that eggs are laid in the midvein of the leaf and young larvae tunnel in the vein until the fall. Remove and destroy mined leaves before May. Adults may be present mid-late May (246-448 GDD’s, base 50°F).
  • Honeylocust Plant Bug: Diaphnocoris chlorionis feeding results in tiny yellowish-brownish spots on leaves, leaf distortion, and in some cases, defoliation. (There are at least 7 species of plant bugs that feed on honeylocust, Gleditsia triacanthos.) There is one generation per year. Immatures and adults feed on foliage and light to moderately damaged foliage may persist throughout the growing season. Honeylocust plant bugs overwinter as eggs laid just beneath the bark surface of 2 and 3 year old twigs. Eggs hatch just after vegetative bugs of the host begin to open. Young nymphs crawl to the opening leaflets and begin feeding and the most significant damage occurs at that time, when the insect is hidden from view. Nymphs develop into adults around May-July. This insect can be targeted between 58-246 GDD’s, base 50°F.
  • Hydrangea Leaftier: Olethreutes ferriferana is a moth in the Family Tortricidae whose caterpillars use silk applied to the edges of two newly expanding hydrangea leaves to tie them together to create an envelope-like structure within which they feed. These leaf-envelopes tend to occur near the tips of plant stems and can be very obvious. As a result, the two tied leaves may not fully expand when compared to healthy, non-impacted leaves. Many envelope or purse-like structures can be seen throughout the plants and may be found from the base to the top of the plant. By gently pulling apart the tied-together leaves, tiny caterpillars are revealed within and able to be mechanically managed by crushing the individual caterpillars.

    Caterpillars are green and partially transparent with a black head capsule and a black thoracic shield which is found on the top of the body segment located directly behind the head. Pupation is thought to occur in the ground nearby host plants, so the insect drops to the ground to pupate where it overwinters. Pupation occurs sometime in June. Adults are found in the spring and are small white and brown moths. Eggs are laid on branch tips of various species of hydrangea. Only one generation is known per year. This insect, although creating visible and interesting damage to hydrangea, is not usually considered to be a serious pest – although occasional localized problematic populations have been reported. Removing leaf-envelopes in the early spring or pinching them to kill the caterpillar within can help reduce populations on individual plants.

  •  Willow Leaf Beetle (T. Simisky) Imported Willow Leaf Beetle: Plagiodera versicolora adult beetles overwinter near susceptible hosts. Adult beetles will chew holes and notches in the leaves of willow once they become available. Females lay yellow eggs in clusters on the undersides of leaves. Larvae are slug-like and bluish-green in color. They will feed in clusters and skeletonize the leaves. Most plants can tolerate the feeding from this insect, and foliage will appear brown. Repeated yearly feeding can be an issue, in which case management of the young larvae may be necessary. Take care with treatment in areas near water. 

Check out Episode 4 of InsectXaminer to see the imported willow leaf beetle in action:

  • Lecanium Scales (Oak): Parthenolecanium quercifex overwinters as a second instar nymph on oak twigs. Females will begin feeding and mature in the spring, from mid-April to early May and eggs may be laid between late May and into June. Eggs hatch in June or early July and crawlers migrate to host plant leaves where they spend the summer and migrate as second instars back to host plant twigs in the fall. 
  • Lilac Borer: Podosesia syringae is a clearwing moth pest of lilac, privet, fringetree, and ash. (It is also known as the ash borer, not to be confused with the emerald ash borer.) Adults mimic paper wasps. Larvae are wood-boring, and signs and symptoms include branch dieback, holes, and occasionally, sawdust-like frass accumulated on bark. Larvae bore into stems, trunks, and branches, chewing an irregularly shaped entrance hole. Peak adult moth flights may occur in the northern portion of this insect’s range in June and is usually over by August 1st. Pheromone traps can be used to time adult emergence. Adult females lay flattened, oval, and tan eggs that are deposited singly or in clusters on bark crevices, ridges, and sometimes smooth bark; but usually laid in or near wounds in the bark. On average, 395 eggs are laid by each female. After hatch, larvae chew into the bark and feed laterally and then vertically in phloem tissue. Larvae overwinter in tunnels in the final instar and resume feeding in the spring. Adults emerge through a round exit hole (4-5 mm. in diameter). This insect may be targeted between 200-299 GDD’s, base 50°F.
  • Lily Leaf Beetle (T. Simisky) Lily Leaf Beetle:Lilioceris liliiadults overwinter in sheltered places. As soon as susceptible hosts such as Lilium spp. (Turk’s cap, tiger, Easter, Asiatic, and Oriental lilies) and Fritillaria spp. break through the ground, the adult lily leaf beetles are known to feed on the new foliage. (Note: daylilies are not hosts.) Adult lily leaf beetles were observed to be active in Hanson, MA on 4/14/2023. Typically, in May, mating will occur and each female will begin to lay 250-450 eggs in neat rows on the underside of the foliage. If there are only a few plants in the garden, hand picking and destroying overwintering adults can help reduce local garden-level populations at that time.  

Check out Episode 3 of InsectXaminer to see the lily leaf beetle in action:

  • Magnolia Scale: Neolecanium cornuparvum overwinters as first instar nymphs which are elliptical, and dark slate gray in color and can usually be found on the undersides of 1 and 2 year old twigs. Nymphs may molt by late April or May and again by early June at which time the scales may be purple in color. Eventually nymphs secrete a white powdery layer of wax over their bodies.
  • Pitch mass created by the activity of the pitch mass borer seen on Norway spruce. Photo courtesy of: Jim Rassman, Service Forester, MA Department of Conservation and Recreation. Pitch Mass Borer: Synanthedon pini is a native clearwing moth whose larvae feed within various pines and spruce. Feeding by the larvae (caterpillars) of this insect causes pitch masses to form on host plants. Two or three years are required for this insect to complete its life cycle, with adult moths present during the summer. Adult pitch mass borer moths may resemble wasps. Adult males and females are blue/black from above, marked with a patch of red/orange on the underside of the abdomen, with some orange on the top of the fourth abdominal segment. Orange is also found along the sides of the abdomen. Forewings are black/blue in color and opaque with wing length of 0.47 to 0.59 inches. Adults are said to emerge, mate, and females lay eggs on their hosts some time in July. By the late summer, the larvae (immatures; caterpillars) bore into their host plant, tunneling through the trunks, often directly beneath a branch. Larvae have uniformly dark brown heads, white bodies, and prolegs with rows of 6-8 crochets on the bottom of their "feet". At the site of the borer wound, large amounts of pitch exude from the tree in a hemispherical mass above the larval tunnels. Larvae continue to feed and develop in the tree through the following year, and it is thought that caterpillars may take up to two years to mature. Masses may be 3-4 inches in diameter. Pupation occurs in a subsequent end of May through June in time for adult emergence by July and August. Pupal cells are formed within the pitch mass and lined with silk (Beuttenmüller, 1901). Pupae are 0.73 inches long and light brown in color (Kellicott, 1881).

    Adult moths are active during the summer. Following egg laying and egg hatch, the larvae tunnel under the bark to the cambium. Obvious, large globs of pitch appear on trunks. Occurs sporadically on individual trees. Host trees with active caterpillars have pitch masses that may appear coated in a white, powdery substance. Larvae may also preferentially bore into the host beneath a broken branch or scar. This insect will attack large trees, up to 30-40 feet from the ground. Healthy trees are also preferentially utilized. Overall damage to the health of the host tree is typically not extensive, and therefore chemical management of this insect is often unnecessary.

    Pitch can be removed and the single larva within destroyed. Physical/mechanical management of this insect, if it can be safely done, is a great way to manage the pitch mass borer on individual specimen trees. The act of just pulling the caterpillar from its pitch mass will kill it - much to the frustration of history's entomologists looking to study them - as soon as contact of the pitch is made with the caterpillar's body and hardens and adheres to them. Parasitism by natural enemies is reported to be relatively common. Parasitic wasps in the family Eulophidae are noted but not specified, as well as a caterpillar-eating species of fly (Engelhardt, 1946).

  • Rhododendron Borer: Synanthedon rhododendri is one of the smallest of the native clearwing moths. Rhododendrons are preferred hosts, although mountain laurel, and deciduous azaleas can be heavily infested, especially if they are planted in close proximity to rhododendrons. Injury may be first noticed in the fall (leaves lose their sheen, then become pale green, then olive, then chlorotic) and can look similar to drought stress. On branches that seem to be stunted, look at limb crotches, scars, and other irregularities for sawdust stuck on bark or on the ground beneath these areas. In late May and early June, holes may contain pupal shed skins extending halfway out. Moth emergence occurs in the late-spring, early-summer. After mating, female moths seek out suitable egg laying locations (preferring wounded areas or limb crotches). The female lays her eggs and dies. Eggs hatch and larvae tunnel into the inner bark where they feed in tunnels that become packed with reddish frass pellets. By late fall, larvae move to the sapwood where they overwinter and resume feeding by mid-March. Pupation occurs in the spring and there is one generation per year. Prune out and destroy infested branches before late May/June. Monitor for adults in mid-May (192-298 GDD’s, base 50°F). 
  • Roseslugs: Two species of sawfly can be found on the leaves of roses at this time. These small, caterpillar-like larvae will skeletonize the upper leaf surface and leave a “window-pane” like pattern behind. When present in large numbers, these insects are capable of defoliating their entire host. Management options include an insecticidal soap spray or a product containing spinosad.

  • Snowball Aphid: Neoceruraphis viburnicola eggs overwinter on viburnum twigs and buds. Eggs hatch and this aphid becomes active on certain species of viburnum roughly between 148-298 GDD’s or around redbud bloom. This insect is particularly noticeable on V. opulus, V. prunifolium, and V. acerifolia. Stem mothers, appearing blueish-white, can be found in curled up and distorted foliage. Damage caused by this insect pest is mostly aesthetic.
  • Spruce Bud Scale: Physokermes piceae is a pest of Alberta and Norway spruce, among others. Immatures overwinter on the undersides of spruce needles, dormant until late March. Immatures overwinter on the undersides of spruce needles, dormant until late March. By April, females may move to twigs to complete the rest of their development. Mature scales are reddish brown, globular, 3 mm. in diameter, and found in clusters of 3-8 at the base of new twig growth. They closely resemble buds and are often overlooked. Crawlers are present around June.
  • Spruce Spider Mite: Oligonychus ununguisis a cool-season mite that becomes active in the spring from tiny eggs that have overwintered on host plants. Hosts include spruce, arborvitae, juniper, hemlock, pine, Douglas-fir, and occasionally other conifers. This particular species becomes active in the spring and can feed, develop, and reproduce through roughly June. When hot, dry summer conditions begin, this spider mite will enter a summer-time dormant period (aestivation) until cooler temperatures return in the fall. This particular mite may prefer older needles to newer ones for food. Magnification is required to view spruce spider mite eggs. Tapping host plant branches over white paper may be a useful tool when scouting for spider mite presence. (View with a hand lens.) Spider mite damage may appear on host plant needles as yellow stippling and occasionally fine silk webbing is visible.
  • Taxus Mealybug: Dysmicoccus wistariae will produce honeydew and lead to sooty mold growth, yellowing of needles, and sparsely foliated plants. Eventual dieback may be possible. This species is commonly associated with taxus in New England, but can be occasionally found on dogwood, rhododendron, Prunus spp., maple, andromeda, and crabapple. These mealybugs are found on stems and branches and particularly like to congregate at branch crotches. Taxus mealybug feeds in the inner bark tissue of the trunk and branches. Adult females are present from June to August and give birth to living young in the summer. Immatures overwinter. A single generation may occur per year in New England, but areas to the south can have multiple generations of this insect. Management may be targeted between 246-618 GDD’s, base 50°F. Horticultural oil and neem oil may be used.
  • Viburnum Leaf Beetle: Pyrrhalta viburni is a beetle in the family Chrysomelidae that is native to Europe, but was found in Massachusetts in 2004. By 2008, viburnum leaf beetle was considered to be present in all of Massachusetts. Larvae are present and feeding on plants from approximately late April to early May until they pupate some time in June. Adult beetles emerge from pupation by approximately mid-July and will also feed on host plant leaves, mate, and lay eggs at the ends of host plant twigs where they will overwinter. This beetle feeds exclusively on many different species of viburnum, which includes, but is not limited to, susceptible plants such as V. dentatum, V. nudum, V. opulus, V. propinquum, and V. rafinesquianum. Some viburnum have been observed to have varying levels of resistance to this insect, including but not limited to V. bodnantense, V. carlesii, V. davidii, V. plicatum, V. rhytidophyllum, V. setigerum, and V. sieboldii. More information about viburnum leaf beetle may be found at and here: .
  • White Spotted Pine Sawyer (WSPS): Monochamus scutellatus adults can emerge in late May throughout July, depending on local temperatures. This is a native insect in Massachusetts and is usually not a pest. Larvae develop in weakened or recently dead conifers, particularly eastern white pine (Pinus strobus). However, the white spotted pine sawyer looks very similar to the invasive Asian Longhorned Beetle, Anoplophora glabripennis, ALB. ALB adults do not emerge in Massachusetts until July and August. Beginning in July, look for the key difference between WSPS and ALB adults, which is a white spot in the top center of the wing covers (the scutellum) on the back of the beetle. White spotted pine sawyer will have this white spot, whereas Asian longhorned beetle will not. Both insects can have other white spots on the rest of their wing covers; however, the difference in the color of the scutellum is a key characteristic. See the Asian longhorned beetle entry above for more information about that non-native insect.
  • Woolly Apple Aphid (T. Simisky) Woolly Apple Aphid: Eriosoma lanigerum may be found on apple, crabapple, hawthorn, mountain ash, Pyracantha, and elm hosts. The primary (winter) host is elm, on which aphids infest emerging spring leaves, causing leaves to curl or close into stunted, rosette-like clusters found at twig tips. On apple and crabapple, this species of aphid colonizes roots, trunks, and branches in the summer and is commonly found near previous wounds or callous tissue. On roots, the aphids cause swelled areas which can girdle and kill roots. The aphids, when found in above ground plant parts such as elm leaves, are covered with white wax. Eggs are the overwintering stage on elm, which hatch in the spring in time for the nymphs to infest new elm foliage. Following a few generations on elm, the aphids will develop into a winged form, which will disperse and seek out apple and crabapple. Multiple generations will occur on these alternate hosts in the summer and by the fall, a winged form will return to elm and mated females will lay eggs near elm buds. These aphids are a favorite snack for insect predators such as the multicolored Asian lady beetle, Harmonia axyridis.
  • Woolly Elm Aphid (T. Simisky) Woolly Elm Aphid: Eriosoma americanum females lay a single egg in the cracks and crevices of elm bark, where the egg overwinters. Eggs hatch on elm in the spring as leaves are unfolding. Aphids may be active from 121-246 GDD’s, base 50°F on elm. Aphids may be active from 121-246 GDD’s, base 50°F on elm. A young, wingless female hatched from the egg feeds on the underside of leaf tissue. This female aphid matures and gives birth to 200 young, all females, without mating. These aphids feed, and the elm leaf curls around them and protects them. By the end of June, winged migrants mature and find serviceberry hosts. Another set of females is produced. These new females crawl to and begin feeding on the roots of serviceberry. Multiple generations occur on the roots of serviceberry through the summer.

Concerned that you may have found an invasive insect or suspicious damage caused by one? Need to report a pest sighting? If so, please visit the Massachusetts Introduced Pests Outreach Project: .

Reported by Tawny Simisky, Extension Entomologist, UMass Extension Landscape, Nursery, & Urban Forestry Program

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Diagnostic Services

UMass Laboratory Diagnoses Landscape and Turf Problems - The UMass Extension Plant Diagnostic Lab is available to serve commercial landscape contractors, turf managers, arborists, nurseries and other green industry professionals. It provides woody plant and turf disease analysis, woody plant and turf insect identification, turfgrass identification, weed identification, and offers a report of pest management strategies that are research based, economically sound and environmentally appropriate for the situation. Accurate diagnosis for a turf or landscape problem can often eliminate or reduce the need for pesticide use. For sampling procedures, detailed submission instructions and a list of fees, see Plant Diagnostic Laboratory

Soil and Plant Nutrient Testing - The University of Massachusetts Soil and Plant Nutrient Testing Laboratory is located on the campus of The University of Massachusetts at Amherst. Testing services are available to all. The lab provides test results and recommendations that lead to the wise and economical use of soils and soil amendments. For more information, including current turn-around times, visit the UMass Soil and Plant Nutrient Testing Laboratory web site. The lab is currently accepting new orders for Routine Soil Analysis (including optional Organic Matter, Soluble Salts, and Nitrate testing), Particle Size Analysis, Pre-Sidedress Nitrate (PSNT), and Soilless Media (no other types of soil analyses available at this time). See for current turnaround time. Please plan for the fact that date of receipt in the lab is affected by weekends, holidays, shipping time, and time for UMass Campus Mail to deliver samples to the lab.

Tick Testing - The UMass Center for Agriculture, Food, and the Environment provides a list of potential tick identification and testing options at:

Acknowledgements: UMass Extension gratefully acknowledges the support of the following funding sources for the production of the Landscape Message –

  • The Massachusetts Nursery and Landscape Association Fund
  • The Massachusetts Department of Conservation and Recreation, Award #ISADCR28219926UMA22A
  • Stakeholders like you! The Landscape Message is partially supported by educational program user fees.